Control shaft



April 16, 1940.

' I M. J. ARVIN I CONTROL SHAFT Filed Feb. 9, 1937 INVENTQR Harm/'2 j flrmn/ ATTORNEjY PatentedApnlB, 1940 r 1 i g Y 2,197,140

I UNITED STATES PATENT O'FFlCE CONTROL SHAFT Marion J. Arvin, Indianapolis, Ind., minor to P. R. Mallory & 00., Inc., Indianapolis, Iml, a corporation of Delaware,

Animation February 9, 1937, Serial No. 124,837

' 2 Claims. (Cl.'64-1) Thisinvention relates to control shafts for elec- For example, one knob used at present using a trical devices. inch shaft requires a flattened side a; of an An object of the invention is to improve the inch below the normal rounded surface of the control shafts for electrical devices. shaft while another type of knob requires a of 6 Another object is to provide a control shaft an inch flattening. Heretofore it has been neceswhich can be adapted to use with a variety of consary either to obtain a knob adapted for the partrol knobs. ticular flattening which the manufacturer has Other objects of the invention will be apparent provided on the shaft or to laboriously file down from the following description and accompanying the shaft to the proper depth for the desired knob.

10 drawing taken in connection with the appended Obviously for purposes of apperance it is not 10 claims. always possible to use the different styles of knobs The invention comprises the features of con interchangeably. struction, combination of elements, arrangement According to the present invention a control of parts, and methods of manufacture and operashaft is provided which is more readily adaptable tion referred to above or which will be brought to the various styles of knobs and hence can be 15 out and exemplified in the disclosure hereinafter used by the parts manufacturer on all the devices set forth, including the illustrations in the drawproduced. Then the shaft can readily and coning. veniently be adapted to any style of knob desired. In the drawing: While a preferred embodiment of the invention Figure l is a side view partly in section of an is described herein, it is contemplated that con- 20 electrical device and the control shaft and considerable variation may be made in the method of trol knob therefor; procedure and the construction of parts without Figure 2 is a section on the line 2-2 of Figdeparting from the spirit of the invention. In ure 1; the following description and in the claims, parts Figure 3 is a section of a portion ofthe control will be identified by specific names for conven- 25 shaft with a modified type of knob attached ience, but they are intended to be as generic in thereto; their application to similar parts as the art will Figure 4 is a section on the line 4-4 of Figpermit. ure 3; Referring to the drawing, Figure 1 shows a. Figure 5 is a section of the control shaft with variable electrical device comprising a radio vol- 30 another form of knob attached thereto; ume control I 0 having a control shaft ll em- Figure 6 is a section on the line 6---6 of Figure bodying features of the present invention and a 5; and control knob l2 secured tothe control shaft by a Figure 7 is a view illustrating the method of set screw l3. adapting the shaft for use with the knob of Fig- Shaft Ii is formed of a cylindrical piece of 35 ure 5. relatively soft metal such as aluminum or the like Ele tr c d Such as those used in radio which has a flat bottomed slot l4 milled therein sets and the like, including volume controls, varilongitudinally to the shaft The bottom of 1; able condensers, switches and the like are usually H may fo example, be approximately s of an provided with control knobs connected to the inch below the normal rounded Surface of the 3:1 3:35; 2235531322335 223533553225 The of as to a the shaft is rotated and this in turn actuates the pan of narrow Walls or ndges and 20 each of moving parts of the electrical devices whose faces corresponds the outer surface of 45 The knobs commonly used for actuating such a g i g :g tj '2 sh ft 45 devices are at present furnished in several types I I as 15 $2; d 2, this 25 g havin different means for attachment to the g narily requires a of an inch flat on the shaft.

control shaft. Thus some knobs are equipped with a set screw f Securing them to the h ft The shaft H is adapted for use with this knob by 5 and others are provided with a spring clip inserting a short rectangular strip of metal IS in In shafts heretofore used it has been customary 51011 Metal P ce i5 is of Such wldth as to fit for the manufacturers to flatten one side of the ead ly nto lot l4 d ofsuch thickness as to shaft to afford a purchase area from the set screw provide a top surface of a height corresponding or spring of the knob. However, different styles to a shaft with a inch flat. Knob I2 can then u of knobs require different degrees of flattening. be slipped over the end of the shaft as illustrated and screw l3 tightened against the surface of metal insert I5. I

Figures 3 and 4 illustrate the use of another form of knob l6 having a spring clip I! for attachment to the shaft. If knob l6 also requires a of an inch flat the shaft II can be adapted for use with it by the insertion. of metal insert I5 in the same manner as before. In this] case spring I! rests against the flat top face of insert Figures 5 and 6 illustrate how the shaft can be adapted for use with another form of knob l6. Knob I8 is a type of knob requiring a 1?; inch fiat on the shaft. In order to adapt shaft II for use with knob l8, therefore, the two side walls I 9 and 20 are scraped or whittled off in any desired manner, for example, as illustrated in Figure 7. This leaves exposed at the end of shaft I I a fiat portion corresponding to the depth of slot It, in other words, a inch flat. It is then possible to slip knob it on to shaft II and spring clip 2| of the knob will then rest on the flat face thus provided. It will thus be seen that applicant has provided a shaft which is readily adaptable to the various types of knobs used without the necessity of laborious filing or other difficult or time consuming operations or without the necessity of providing special shafts for each type of knob. This is a decidedly great convenience.

It will be obvious that the shaft illustrated can be adapted for use with other types of knobs and that the dimensions given are merely for the purpose of illustration and that these dimensionsv can be varied as required. It will be noted that the shaft H is shown in different sizes in the various figures for purposes of better illustration;

It is intended, however, that the same shaft be v considered as represented in all the views.

Another advantage of the shaft illustrated re- 2,197,140 7 V v t to cut themto length with a saw- With-the hm: ent shaft it is only necessary to notch the shaft at the point where a breakis -desired and then 1 to breakit.

While the shaft is here illustratedias'applied to a radio volume controlit will be obvious that x it is also adapted for use with a variety of other 1 electrical devices such as variable condensers-and i electric switches. I

'Whiie the presentinvention as t'oits objects and advantages. has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby-but it. is .in-'

cylindrical shaft of soft metal formed with a longitudinal slot along one side thereof, said slot being defined by a pair of narrow ridgesdefining said slot between them, whereby said shaft may be. readily adapted for use with a plurality of types of control knobs by insertion of a block in said slot or by whittling off said ridges at the point of intended engagement with the knob.

2. An adaptable control shaft for actuating variable electric devices of the type comprising radioset volume controls and the like, said shaft being adaptable to a plurality of types of control knobs and comprising an elongated cylindrical 'body offsoft metal having a longitudinal slot along one side thereof, said slot being defined by a pair of narrow ridges defining said slot between them, said ridges and slot extending to the knob and of said shaft, whereby said shaft end may be readily adapted for use with any of said types of knobs by insertion of .an adapter block in said slot or by whittling away said ridges as required.

MARION J. ARVIN. 

